1. Field of the Invention
This invention relates to order processing in a warehouse and, more particularly, to a system for processing orders using a pick and pass process. The invention is further directed to a method of processing orders using the system.
2. Background Art
Order picking in warehouse operations has been closely scrutinized in recent years. This arises from the increased emphasis on new operating concepts such as just-in-time, quick response, and new marketing strategies. These strategies require that: a) more stock keeping units are available; and b) small orders are delivered with greater frequency and accuracy. The overall goal of such systems is increase in throughput, storage, and accuracy.
While order picking techniques vary greatly, they are generally classified into three main areas: a) pallet picking; b) case picking; and c) piece picking, also referred to as broken case picking.
In broken case picking systems, individual items are picked from stored locations. Piece pick operations generally have large stock keeping unit bases in the thousands, or tens of thousands, of items. These operations typically have small quantities per pick and short cycle times.
Pick and pass order picking, also known as zone picking, is the order picking version of an assembly line. In zone picking, the picking order is broken up into individual pick zones. Order pickers are assigned a specific zone and pick only from within that zone. Orders are assigned to one tote, or multiple totes. After an order is assigned, the tote(s) is inducted and moved from one zone to the next as the picking from the previous zone is completed until all picks for the tote are completed. The operator will then push the tote onto a take-away conveyor when all the items at that zone have been picked.
With pick and pass operations, it is important to balance the number of picks from zone to zone to maintain a consistent flow. Conveyors are used to move totes between zones. Zones are typically sized to accommodate enough picks for one or two order pickers. Additionally, to maintain high production and efficiency, pick zones need to be sized so that the travel time between zones is kept to a minimum.
Historically, flow rack technology has been the industry standard for pick and pass operations. In these systems, shelves are mounted at a slight angle to allow items to be moved by gravity towards a pick location. Items are re-stocked from the rear of the flow rack and picking is done from the front face. Flow rack technology is useful when there is a high volume of picks per stock keeping unit. Flow rack technology typically is appropriate for medium to fast moving stock keeping units. Slow moving stock keeping units do not generally perform well due to the fact that the picking operator has to walk too far between picks. This problem has long existed and continues to exist.